Online wet chemistry analyzers are used in a variety of industries to provide a continuous indication of an analyte in a process sample. This continuous indication can be provided locally by the analyzer and/or remotely to one or more suitable devices in order to provide control and/or monitoring of a chemical process.
One particular example of an online wet chemistry analyzer is an online automatic colorimetric analyzer. Such devices are configured to generate a reaction in the process sample that creates a visual indication relative to the process sample. This visual indication is measured by an optical sensor or light detector in order to provide an indication relative to the reaction. Colorimetric analysis is used in a variety of settings ranging from medical laboratories to industrial wastewater treatment facilities. Such analysis may be used with or without an enzymatic stage and is applicable to detecting both inorganic and organic compounds. Colorimetric techniques are known for detecting calcium, copper, creatine, iron, phosphate, cholesterol, glucose, urea, trigylcerides, and silica.
One particular example of an automatic colorimetric analyzer is an online silica analyzer that employs a known reaction to render the silica in the process sample readily detectable. One example of such a reaction is known as the molybdenum blue method. In the molybdenum blue method, molybdate (usually in the form of potassium molybdate) is used to react with silica in the process sample in order to generate a compound suitable for colorimetric detection. In accordance with the molybdenum blue method, the silica content in water is measured based on the color of the silicomolybdic acid formed through the wet chemistry process. The molybdenum blue method can also be used for colorimetric qualitative analyses of phosphorous, arsenic, and germanium.
In online wet chemistry analyzers that utilize optical measurement techniques, it is important to facilitate an effective optical measurement. Aspects or properties of the sample or reagents that may interfere with the optical measurement that are not related to the presence or concentration of the analyte, generate measurement errors. Therefore, identifying and/or reducing such artifacts is beneficial in order to obtain higher precision and fidelity in optical colorimetric measurements.